Aperture vs Depth of Field: photography cheat sheet

What is aperture, you might be wondering if you’re new to photography? Your digital camera’s aperture is simply a hole in the lens – a variable diaphragm that can be made larger or smaller – to control how much light reaches the sensor. In this quick tutorial we will explain what you need to know to get started taking more control of your depth of field, photography skills and when you can put these into practice.

You control the aperture size using the dial on your DSLR (or it is set for you by the camera). The aperture size is measured on the f/stop scale.

The numbers on this scale can be hard to understand; f/8 is larger than f/16, as they are actually fractions, so f/8 is an eighth, and f/16, a sixteenth.

Your choice of apertures will vary depending on the lens you are using, but will generally range from a widest setting of around f/4 (as seen in the portrait above) to a narrowest of around f/22 (as seen in the image at the top of this page); some lenses will offer a wider or narrower range of values.

The aperture also jumps in a seemingly illogical steps – which ultimately you will just have to get used to. The key sequence to remember is the ‘full stop’ range – f/4, f/5.6, f/8, f/11, f/16 and f/22.

Each step along halves the amount of light reaching the sensor (and this can be compensated by doubling the shutter speed).